In a two-cycle gasoline engine the combustible mixture flows into the cylinder at the crankcase side of the piston when the piston is adjacent the cylinder head. As the engine fires and the piston moves toward the crankcase, this combustible mixture then is compressed in the crankcase. When the piston approaches its extremity of travel closest to the crankcase, it uncovers a port in the cylinder wall, which port is a part of a transfer duct communicating with the crankcase. This allows the combustible mixture which has been compressed in the crankcase to flow into the cylinder, between the piston and the cylinder head. Of course, not all of the combustible mixture in the crankcase will be exhausted therefrom and into the cylinder. The principal object of the present invention is to improve the performance of the engine by increasing the amount of the combustible mixture that moves from the crankcase into the cylinder.
The rotation of the crankshaft in the crankcase acts much in the nature of a blower fan to cause a rotation in the same direction of the combustible mixture. This is all the more true in those two-cycle engines which have one or two cylindrical flywheels in the crankcase as a part of what may be referred to as the crankshaft. Furthermore, in these latter type of engines there is a "boundary layer" of the combustible mixture immediately adjacent the periphery of the flywheel(s) and rotating therewith at approximately the same speed as the flywheel(s). In the present invention, vanes are positioned in the crankcase to deflect this rotating air into the port forming the crankcase end of the transfer duct. In those engines having the flywheel in the crankcase, this vane structure is positioned immediately adjacent the periphery of the flywheel so that the boundary layer is skimmed or scooped from its position adjacent the flywheel periphery and directed toward the transfer duct. Thus in utilizing the present invention the charging of combustible mixture into the cylinder is accomplished not only as a result of the compression of the combustible mixture in the crankcase, but also as a result of the force occasioned by the rapidly moving (in a rotating direction) combustible mixture in the crankcase. Thus the power of a given two-cycle engine is increased due to the increased charge of combustible mixture in the cylinder.